Hemodynamic stability during 17 years of the Carpentier-Edwards aortic pericardial bioprosthesis

BACKGROUND: Long-term stability of the hemodynamic performance of commercially available Carpentier-Edwards stented bovine pericardial aortic bioprostheses (Perimount RSR) is unknown. To anticipate the fate of this bioprosthesis, we examined its hemodynamic performance up to 17 years using echocardiographic studies in a Premarket Approval cohort. METHODS: Of 267 patients at four institutions in the Premarket Approval cohort, 85 had a total of 168 echocardiographic studies during a 17-year period of yearly follow-up examinations. These were reviewed and quantified in a core echocardiographic facility. Longitudinal data analysis was used to account for repeated, censored data. RESULTS: Mean transvalvular gradient was inversely related to prosthesis size (p = 0.01), and possibly (p = 0.06) increased somewhat during the first 10 years of follow-up, then stabilized. Effective orifice area was larger in larger valve sizes (p = 0.01), declined somewhat during the first 10 years, and then began to increase again. Ejection fraction declined minimally (p = 0.2). In contrast to the rather stable hemodynamics, aortic regurgitation steadily increased from none to 1 to 2+ (p = 0.005), but rarely (< 10% at 17 years) progressed to 3+ or 4+. CONCLUSIONS: The Carpentier-Edwards aortic pericardial bioprosthesis can be anticipated to have an acceptable long-term transvalvular gradient and effective orifice size that will change trivially up to 17 years after implantation. Mild aortic regurgitation will develop progressively. This anticipated hemodynamic resilience supports continued clinical use of the Perimount Carpentier-Edwards bovine pericardial stented bioprosthesis.     

Endocarditis after mitral valve repair

Background. Native valve endocarditis is frequently managed with antibiotics alone, but prosthetic valve endocarditis usually requires an early operation. What is the best treatment of endocarditis after mitral valve repair?

Methods. From 1986 to 2000, 22 patients were treated for endocarditis affecting a previously repaired mitral valve. Causes of mitral valve dysfunction that led to repair were degenerative (11 patients), ischemic (5 patients), endocarditic (3 patients), rheumatic (2 patients), and functional (1 patient). Endocarditis was active in 21 patients and healed in 1. Interval from initial mitral valve repair to onset of endocarditis ranged from 1 week to 10.3 years (median, 6 months). Pathology included leaflet vegetation (15), annuloplasty vegetation (4), leaflet perforation (5), and abscess (3). Mean follow-up was 3.9 ± 3.3 years.

Results. Fifteen patients underwent repeat mitral valve operations with freedom from mitral valve reoperation of 65%, 41%, and 26% at 30 days, 1 year, and 5 years after onset of endocarditis. After a high early hazard, risk of reoperation fell to 10.8% per year. Seven patients, all with a leaflet vegetation, were treated with antibiotics alone. Antibiotics eradicated infection in all; however all had mitral regurgitation 2+ to 4+. Survival was 96%, 74%, and 68% at 30 days, 1 year, and 5 years. Endocarditis recurred in 1 patient (92% free of event).

Conclusions. Most patients that have endocarditis develop after mitral valve repair require reoperation. However if infection is limited to a leaflet, early reoperation may be unnecessary because antibiotics alone can eradicate infection.     

Microwave ablation of atrial fibrillation during mitral valve operations

Although the Cox-Maze III procedure cures atrial fibrillation in the majority of patients, it has not had widespread application. Development of new operations that use alternate energy sources and different lesion sets have caused resurgence in the surgical treatment of atrial fibrillation. Microwave creates lines of conduction block by thermal damage and subsequent scar formation. We describe a rapid and simple technique for microwave ablation of atrial fibrillation in patients having mitral valve operations.     

Reoperative cryopreserved root and ascending aorta replacement for acute aortic prosthetic valve endocarditis

BACKGROUND: Prosthetic aortic valve endocarditis (PVE) is an important complication of aortic valve replacement (AVR) and is a particularly difficult situation after an operation combining AVR with ascending aortic replacement. METHODS: From 1988 through 2000, 27 patients with aortic valve PVE after previous ascending aortic replacement (aortic root replacement in 13, aortic valve replacement with a supracoronary graft in 14) underwent reoperation for aortic root replacement with a cryopreserved aortic allograft and prolonged intravenous antibiotic therapy. All patients were considered to have active PVE (25 with positive cultures); root abscess formation was present in 89% and aortoventricular discontinuity in 41%. RESULTS: One patient (3.7%) died in-hospital, and permanent pacemakers were required in 10 patients (37%). Mean postoperative follow-up interval was 3.9 +/- 3.0 years, and survival at 1, 2, 5, and 7.5 years was 92%, 88%, 70%, and 56%, respectively. One patient underwent reoperation for recurrent PVE 8 months after operation. CONCLUSIONS: Radical debridement of infected prosthetic material and tissue, and allograft aortic root and ascending aorta replacement, combined with intravenous antibiotic therapy, appears to achieve a low hospital mortality and a high degree of freedom from recurrent infection for patients with PVE after AVR and ascending aortic replacement.     

Potential improvements in the therapeutic ratio of prostate cancer irradiation: dose escalation of pathologically identified tumour nodules using intensity modulated radiotherapy

The potential of intensity modulated radiotherapy (IMRT) to improve the therapeutic ratio in prostate cancer by dose escalation of intraprostatic tumour nodules (IPTNs) was investigated using a simultaneous integrated boost technique. The prostate and organs-at-risk were outlined on CT images from six prostate cancer patients. Positions of IPTNs were transferred onto the CT images from prostate maps derived from sequential large block sections of whole prostatectomy specimens. Inverse planned IMRT dose distributions were created to irradiate the prostate to 70 Gy and all the IPTNs to 90 Gy. A second plan was produced to escalate only the dominant IPTN (DIPTN) to 90 Gy, mimicking current imaging techniques. These plans were compared with homogeneous prostate irradiation to 70 Gy using dose-volume histograms, tumour control probability (TCP) and normal tissue complication probability (NTCP) for the rectum. The mean dose to IPTNs was increased from 69.8 Gy to 89.1 Gy if all the IPTNs were dose escalated (p=0.0003). This corresponded to a mean increase in TCP of 8.7-31.2% depending on the alpha/beta ratio of prostate cancer (p<0.001), and a mean increase in rectal NTCP of 3.0% (p<0.001). If only the DIPTN was dose escalated, the TCP was increased by 6.4-27.5% (p<0.003) and the rectal NTCP was increased by 1.8% (p<0.01). In the dose escalated DIPTN IMRT plans, the highest rectal NTCP was seen in patients with IPTNs in the posterior peripheral zone close to the anterior rectal wall, and the lowest NTCP was seen with IPTNs in the lateral peripheral zone. The ratio of increased TCP to NTCP may represent an improvement in the therapeutic ratio, but was dependent on the position of the IPTN relative to the anterior rectal wall. Improvements in prostate imaging and prostate immobilization are required before clinical implementation would be possible. Clinical trials are required to confirm the clinical benefits of these improved dose distributions.     

Effect of a rigid ankle-foot orthosis on hamstring length in children with hemiplegia

Eighteen children with hemiplegia, mean age 8 years 5 months, underwent gait analysis and musculoskeletal modelling using specially designed software. The maximum lengths of the hamstrings were determined for each child walking in and out of an ankle-foot orthosis (AFO). The muscles were deemed to be short if shorter than the normal average -1SD. In bare feet 8 participants had short medial hamstrings with a higher proportion of these in the less involved individuals. All participants showed an increase in maximum hamstring length when wearing an AFO. In all but one child this was sufficient to restore hamstring length to within normal limits. These finding suggest that hamstring pathology in hemiplegic gait is usually secondary to more distal lower limb pathology.     

Hemisternotomy approach for aortic and mitral valve surgery

After exploring several less invasive approaches for cardiac valve surgery, we have concluded that the partial upper sternotomy is the incision of choice for minimally invasive aortic and mitral valve surgery. From March 1997 to January 1999, 827 patients had cardiac valve surgery using this approach; 462 had mitral valve procedures and 365 had aortic valve procedures. Of those having mitral valve surgery, 87% had mitral valve repair. Aortic valve surgery included replacement with stented bioprostheses (38%), allografts (29%), and mechanical prostheses (10%); in addition, 23% had aortic valve repair. Operative mortality was 0.8%. Conversion to full sternotomy was necessary in 2.4%. Blood use was low with 80% of patients receiving no blood transfusions. We conclude that all primary mitral and aortic procedures can be accomplished safely via partial upper sternotomy.     

Outcomes following staged bilateral pallidotomy in advanced Parkinson's disease

The authors assessed clinical outcome for up to one year after staged bilateral pallidotomy in 14 patients with advanced PD. One year after surgery, dyskinesias were virtually abolished and there were significant reductions in "off" time (67%) and activities of daily living "off" scores (24%), as well as nonsignificant reduction in "off" motor score (39%); "on" scores were unchanged. One patient developed a visual field deficit; two had transient confusion. Staged bilateral pallidotomy improves motor function in selected patients with advanced PD.     

Alfentanil-induced epileptiform activity: a simultaneous surface and depth electroencephalographic study in complex partial epilepsy

PURPOSE: Alfentanil is a high potency mu opiate receptor agonist commonly used during presurgical induction of anesthesia. This and other opiate receptor agonists have demonstrated proconvulsant effects in animals, but these properties have been less consistently demonstrated in humans. Most human scalp EEG studies have failed to demonstrate induction of epileptiform activity with these agents, which is inconsistent with findings using intracranial EEG. Simultaneous scalp and depth EEG recordings have yet to be performed in this setting. The relationship between opiate dose and proconvulsant activity is unclear. METHODS: Simultaneous scalp and depth electrode recordings were performed on five patients with complex partial epilepsy (CPE) who underwent alfentanil anesthesia induction before depth electrode removal. Consecutive equal bolus doses of alfentanil were administered to each patient according to strict time intervals so as to assess their correlation with any induced epileptiform activity. RESULTS: Epileptiform activity was induced by alfentanil in three of five patients. Two of these patients had electrographic seizures. Epileptiform activity was only detected from the depth electrodes, occurring within 2 min of the first bolus dose in all three cases. Further increase or spread of epileptiform activity did not occur despite cumulative bolus doses of alfentanil. CONCLUSIONS: Alfentanil is proconvulsant in patients with CPE. Induced seizures may be subclinical and lack a scalp EEG correlate. There is a complex dose-response relationship. Alfentanil induction of anesthesia should be approached with caution in patients with CPE.